A hard nut to crack: breeding the next generation of disease-resistant hazelnuts

As worldwide production of hazelnuts is threatened by the fungus Eastern Filbert Blight, Rutgers scientists are working on breeding the next generation of fungus-resistant hazelnuts. Although 25 percent of the world’s hazelnuts are purchased by Ferrero, hazelnuts are also in high-demand as important health foods.

To create a fungus-resistant breed of hazelnut trees that would kick-start a whole new agricultural industry in New Jersey, scientists at Rutgers University need to play the long game.

Thomas Molnar, an associate professor in the Department of Plant Biology at Rutgers University, spearheads this ambitious project, first started by the late C. Reed Funk, a former professor in the Department of Plant Biology and Pathology at Rutgers.

“Dr. Funk started the program, his interest was to see what new industry could we start in New Jersey. He grew a whole bunch of things — saw hazelnut grow well and is easily marketed. Tom worked with him, he did his undergrad here,” said Janine Tobia, a School of Environmental and Biological Sciences senior.

“It’s Molnar’s mission to make a successful hazelnut industry in New Jersey,” she said.

Around 25 percent of the world’s hazelnuts are purchased by Ferrero, the company that makes the popular chocolate hazelnut spread Nutella.

Molnar is quick to point out that there is more to their hazelnut program than preserving the world’s supply of Nutella, and said that hazelnuts are an important health food and are very much in demand.

According to Statista.com, the per capita consumption of shelled nuts in the U.S. has increased from 2.61 pounds in 2000 to 4.08 pounds in 2015.

Worldwide demand for hazelnuts is growing, but its ability to grow in the East Coast is hindered by the presence of Eastern Filbert Blight, a regional fungus that destroys the commercial hazelnut populations.

“Eastern Filbert Blight has an incubation period, 16-18 months later is when the plant starts to display canker symptoms, then within three to five years the plant is usually completely dead,” said Justin Lombardoni, a second-year graduate student in the Department of Plant Biology.

The team believes that the best way to defeat the fungus is to breed hazelnuts that are resistant. Breeding resistance into the tree is a lot more cost effective in the long term than using fungicides or any other methods, Tobia said.

Alex Mayberry, a second year graduate student in the Department of Plant Biology, is involved with breeding the new Blight-resistant hazelnuts.

“I work with the American hazelnut, which is a wild native plant very closely related to the European hazelnut, which is the commercial type,” Mayberry said.

The interesting thing about the American hazelnut is that it is naturally resistant to the Eastern Filbert Blight, Mayberry said.

Most people would not want to spread the wild American hazelnuts on their toast.

“They’re not as tasty as the European hazelnuts. They have a thicker shell, they’re harder to crack. Some of them don’t have as high a yield. They’re tiny, they don’t fall from the husk, so it’s harder to harvest,” Mayberry said.

There is no quick way to create a hazelnut breed that is both Blight-resistant and tasty. The team has to collect a lot of samples, plant them in the Garden State then see what happens. Mayberry estimates that the lab has around 2,000 seedlings, either donated by others or collected.

“(The team) just goes around and they would collect from orchards that people were actually cultivating, they would go to markets and collect nuts. They would just get them from as wide a range as they could,” Lombardoni said.

Lombardoni’s research focuses on diversity of European hazelnuts, which involved collecting hazelnut specimens from the Republic of Georgia. “We spent about a week touring around the different orchards in Georgia,” he said.

Molnar estimates that the team has 10 acres of land near Rutgers, solely devoted to growing hazelnuts.

“There are a couple of fields right up on Ryder’s Lane and they have an extension farm at Cream Ridge. They just plant (the seedlings) and whether or not we like it they will be exposed to this fungus, because it’s pervasive,” Lombardoni said.

Any surviving hazelnut trees have fungus resistance. The breeding efforts involve crossing those plants with resistance with those that have nuts with ideal characteristics, he said. Then scientists simply hope that the offspring have both the resistance and the good qualities.

“Generally we wait a year or two before we plant them out in the field. Then you can get phenology data: when the leaves fall, change color, flowering times. You’d have to wait four or five years before you get the nuts,” Mayberry said.

Tobia is a microbiologist by training and concentrates her research efforts on the fungus itself. She looks at the population diversity of the fungus. Her team is trying to see if certain portions of this population have more virulence than others, Tobia said.

“I’ll get a twig with cankers on it, sterilize the surface, scrape off the top of that and inside you have the fungal spores, which is what we can extract DNA from,” she said. She can then look for genetic differences between fungi strains.

The team hopes to understand on a genetic level what causes fungus resistance, but that is no substitute for successfully growing their hazelnuts in the field.

It takes four or five years to learn if a particular hybrid hazelnut breed inherited the right mix of traits, but the team is confident they are moving in the right direction.

“If you can visualize the low range of traits that are acceptable for European hazelnuts … the best American hazelnuts are within the acceptable range of the commercial varieties,” Mayberry said.

Molnar is poised to distribute fungus-resistant hazelnut specimens to New Jersey farmers to see how they perform. He estimates over 1,000 plants are going across the state to at least 10 farms.